for determining the difference of meridians , &c. 117 
Rates of the Chronometers from the 21st to the 2 2d. 
Baker, No. 744. 
Z— C = 8 h o m 47 s, 04 Z,= i7 h 47 m 55 s -62 
Z — - C = 7 56 48 *40 Z = 1 7 38 56 * 1 o 
]Q = 
-I - s 58 ’64 
+ 
3 m 583-64 
24“ 8 m S 9 s ‘ 5 z 
= — 3 m 57*’l6 
8 59 '52 
-f- 24 h 
Being a rate of — i s *25 on mean time. 
The rates originally assigned to the chronometers on leav- 
ing Paris and London, were respectively (on mean time), 
Motel No. 39 , + ! s - 8. Baker 744, + i s -2o. 
The former, then, in the interval must have altered its rate 
(if that deduced from the observations of the 18th and 19th 
be correct), no less than — Y'63 ; and between the 18th and 
21st, must have again accelerated its daily rate by s a, si 9 
fluctuations not to be supposed in a chronometer of any cha- 
racter. It is therefore probable that the rate - — 5 S, 83 of the 
18th- 19th is incorrect, and the observations being positive, 
and liable to no errors capable of accounting for so large a 
deviation, the cause, on this supposition, can lie nowhere but 
in some accidental derangement in that interval. Now it 
unfortunately happens, that the interval B — B', on the 18th, 
to which this suspicious rate is to be applied, is no less than 
4i m 20 s ‘ 6, which produces a correction of — o Si i7 ? or nearly 
two-tenths of a second in the result of that night’s obser- 
vations. 
If we examine the individual observations of both nights, 
on which this rate depends, we shall find no satisfaction, 
though they tend to confirm the suspicion of a derangement 
